JP2017172777A - Air spring structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To homogenize inner pressure in a first end chamber and a second end chamber which are defined in a cylinder by a simple constitution.SOLUTION: An air spring structure has a first communication hole (9) formed at a peripheral face of a cylinder (21) and a second communication hole (9) formed at a peripheral face of the first communication hole (9) at an axle side. A piston (23) has a slide part (23E) which abuts on an internal peripheral face of the cylinder (21), and partitions an inner chamber (50) and a balance chamber (70). A length of the slide part (23E) in an axial direction is shorter than a length between the first communication hole (9) and the second communication hole (9) in the axial direction, and a communication member (8) has a communication path (8A) which is formed for making the inner chamber (50) and the balance chamber (70) communicate with each other while passing the first communication hole (9) and the second communication hole (9).SELECTED DRAWING: Figure 4

Description

  The present invention relates to an air spring structure, and more particularly to an air spring structure provided on a front fork that is mounted on a front wheel side of a two-wheeled vehicle and absorbs road surface vibrations input to the front wheel.

  A cylinder whose first end is a closed end, a rod which is inserted into the cylinder through the second end of the cylinder so as to be able to protrude and retract, and slidably received in the cylinder. A piston held at the tip of the rod, and a first end chamber and a second end chamber defined in the cylinder by the piston, and the first end chamber and the second end chamber are respectively An air spring structure having an air spring is known as a prior art (Patent Document 1 and Patent Document 2).

  In this air spring structure, a passage or an annular groove as a resetting means for resetting the internal pressure of the cylinder is provided in the sliding area of the piston on the inner peripheral surface of the cylinder, and the passage or the annular groove is provided with the above-mentioned When the piston is aimed, communication between the first end chamber and the second end chamber is allowed, and the internal pressures in the first end chamber and the second end chamber are made uniform.

Japanese Patent No. 4557531 Patent No. 5180153

  However, in the prior art as described above, it is necessary to form a passage or a groove on the inner peripheral surface behind the opening end of the elongated cylinder in order to equalize the internal pressure in the first end chamber and the second end chamber. For this reason, there exists a problem that manufacture and a structure of a cylinder become complicated.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to equalize the internal pressure in the first end chamber and the second end chamber defined in the cylinder with a simple configuration. It is to realize an air spring structure.

  In order to solve the above problems, an air spring structure according to the present invention includes a cylinder having a first end as a closed end, a rod inserted in the cylinder from the second end of the cylinder in the axial direction, A piston that is held by a rod and slides on the inner peripheral surface of the cylinder; and a communication member that is provided on the outer peripheral surface of the cylinder. The cylinder is formed as an air spring on the first end side of the piston. A first end chamber, at least a part of a second end chamber formed as an air spring on the second end side of the piston, a first communication hole formed in a peripheral surface of the cylinder, and the first communication A second communication hole formed in the peripheral surface on the second end side of the hole, and the piston contacts the inner peripheral surface of the cylinder, and the first end chamber, the second end chamber, A sliding portion for separating the sliding portion, and the axial length of the sliding portion is The communication member is shorter than the axial length between the communication hole and the second communication hole, and the communication member passes through the first communication hole and the second communication hole, and the first end chamber and the second end chamber. It has the communicating path formed in order to make it communicate with.

  The present invention has an effect that the internal pressure in the first end chamber and the second end chamber defined in the cylinder can be made uniform by a simple configuration outside the cylinder.

(A) is a figure which shows the structure of the motorcycle carrying the front fork which concerns on Embodiment 1. FIG. Moreover, (b) is a figure which shows the structure of a front fork. It is sectional drawing of the 1st fork leg provided in the front fork, (a) is sectional drawing of a compression state, (b) is sectional drawing of an expansion | extension state. It is an expanded sectional view of the piston periphery provided in the 1st fork leg shown in FIG.2 (b). It is an expanded sectional view of the principal part of the piston periphery shown in FIG. It is the fragmentary perspective view which looked at the communication member provided in the said 1st fork leg from the inner side. It is the fragmentary perspective view which looked at the cylinder with which the said communication member was attached from the inner side. FIG. 4 is a schematic diagram for explaining a relationship between a communication hole formed in the cylinder of the first fork leg according to the first embodiment and a communication path formed in the communication member. 6 is a graph showing air reaction force characteristics of the first fork leg according to the first embodiment. It is the fragmentary perspective view which looked at the cylinder to which the communicating member of the 1st fork leg concerning Embodiment 2 was attached from the inside. FIG. 10 is a schematic diagram for explaining a relationship between a communication hole formed in the cylinder of the first fork leg according to the second embodiment and a communication path formed in the communication member. It is a graph which shows the air reaction force characteristic of the front fork which concerns on a comparative example.

(Embodiment 1)
(1-1. Overall configuration of front fork 4)
FIG. 1A is a diagram showing a configuration of a motorcycle 1 equipped with a front fork 4 according to the first embodiment. Further, (b) is a diagram showing a configuration of the front fork 4.

  A motorcycle 1 shown in FIG. 1 (a) includes a vehicle body 2, a front wheel 14A attached to an axle disposed in front of the vehicle body 2, and a rear wheel 14B attached to an axle disposed in the rear of the vehicle body 2. A rear suspension 3 that connects the vehicle body 2 and the rear wheel 14B, a front fork 4 that connects the vehicle body 2 and the front wheel 14A, and a handle 5 for steering the motorcycle 1 are provided.

  The front fork 4 connects the front wheel 14A to the vehicle body 2 such as a two-wheeled vehicle or a three-wheeled vehicle, for example, and cushions an impact and transmits steering of the handle 5 to the front wheel 14A. In the present embodiment, as shown in FIG. 1B, the front fork 4 includes a first fork leg 11A, a second fork leg 11B, a first bracket 12A, a second bracket 12B, and a steering shaft 13. It has.

  The first fork leg 11A and the second fork leg 11B are disposed on the left and right sides of the front wheel 14A so as to face each other with the front wheel 14A interposed therebetween, and rotatably support the front wheel 14A via the axle 14S. Further, the first fork legs 11A and the second fork legs 11B are configured to be extendable and contractable in the axial direction. In the present embodiment, in the following description, the longitudinal direction of the first fork leg 11A is referred to as an “axial direction”.

  The first fork leg 11A incorporates an air spring. In the present embodiment, the first fork leg 11A does not include a damping mechanism. Details of the first fork leg 11A will be described later.

  The second fork leg 11B incorporates a damping mechanism such as an oil damper. However, the configuration of the second fork leg 11B is not limited to this, and may be the same as that of the first fork leg 11A, for example.

  The first bracket 12A and the second bracket 12B connect the first fork leg 11A and the second fork leg 11B. Both ends of the steering shaft 13 are fixed to the first bracket 12A and the second bracket 12B. The steering shaft 13 is connected to the vehicle body 2 so that the front fork 4 can be steered (rotated) to the vehicle body 2. Has been.

(1-2. Configuration of the first fork leg 11A)
(1-2-1. Basic configuration)
FIG. 2 is a cross-sectional view of the first fork leg 11A provided on the front fork 4. FIG. 2A is a cross-sectional view in a compressed state, and FIG. 2B is a cross-sectional view in an expanded state.

  As shown in FIG. 2, the first fork leg 11 </ b> A includes an axle side fixing portion 6, a vehicle body side blocking member 7, an outer tube 15, an inner tube 16, a cylinder 21, a rod 22, a piston 23, A rod guide 36 and a plurality of air spring chambers (inner chamber 50 (first end chamber), outer chamber 60, balance chamber 70 (second end chamber)) are provided.

  In the first fork leg 11A, for example, the axle side fixing portion 6 is connected to the axle side of the motorcycle, the vehicle body side of the first fork leg 11A is connected to the frame of the motorcycle, and the rod 22 is connected to the axle side fixing portion. 6, the cylinder 21 is fixed to the vehicle body side blocking member 7, thereby constituting the front fork 4 in which the rod 22 is positioned downward and the cylinder 21 is positioned upward.

  The axle side fixing portion 6 includes a bracket 32, a bottom piece 33, and a bottom bolt 34. The bottom piece 33 is attached to the opening so as to seal the opening on the axle side of the inner tube 16. The bracket 32 includes a connection hole 32B for connecting the axles.

  The bottom bolt 34 is provided with a pressure adjusting portion 65 that communicates with the internal space of the rod 22. The pressure adjusting unit 65 prevents the gas from flowing out from the internal space of the rod 22 to the outside, and the compression ratio of the gas in the balance chamber 70 via the gas chamber 22U (second end chamber) inside the rod 22. Can be adjusted.

  The vehicle body side blocking member 7 includes a cap 30 and a bolt portion 31 that block the opening on the vehicle body side of the outer tube 15 and the cylinder 21 in an airtight state. The vehicle body side of the first fork leg 11A is connected to the vehicle body of the motorcycle via, for example, the first bracket 12A, the second bracket 12B, and the steering shaft 13. In the vehicle body side closing member 7, an airtight state between the outer tube 15 and the cylinder 21 and the outside is maintained by seal members 61 </ b> A and 61 </ b> B such as an O-ring.

  The bolt portion 31 is provided with an inner chamber pressure adjusting portion 53A for adjusting the enclosed pressure in the inner chamber 50 and an outer chamber pressure adjusting portion 53B for adjusting the enclosed pressure in the outer chamber 60. .

  The inner tube 16 is a cylindrical member, and the axle side is fixed to the axle side fixing portion 6 so that the axle side opening is sealed. The outer tube 15 is also a cylindrical member, and the vehicle body side blocking member 7 is fixed to the vehicle body side so that the opening on the vehicle body side is sealed. The end of the inner tube 16 on the vehicle body side is inserted into the outer tube 15 through the opening on the axle side of the outer tube 15.

  A seal member 13C, a dust seal 13D, and a bush 13B are provided on the inner peripheral surface of the outer tube 15 on the axle opening side, and a bush 13Z is provided on the outer peripheral surface of the inner tube 16 on the vehicle body opening side. The outer peripheral surface of the inner tube 16 and the inner peripheral surface of the outer tube 15 are configured to be slidable while maintaining an airtight state via the bushes 13Z, 13B, the seal member 13C, and the dust seal 13D.

  The inner tube 16 and the outer tube 15 are configured to be relatively movable along the central axis 17 of the inner tube 16 and the outer tube 15. The axle side fixing portion 6 and the vehicle body side blocking member 7 move in directions toward each other in the compression side stroke, and move in directions away from each other in the extension side stroke.

  Further, the first fork leg 11 </ b> A has a cylinder 21 formed in a cylindrical shape with a smaller diameter than the inner diameter of the inner tube 16 inside the outer tube 15 and the inner tube 16, and a smaller diameter than the inner diameter of the cylinder of the cylinder 21. And a rod 22 formed in a cylindrical shape.

  The axle side of the rod 22 is fixed to the axle side fixing part 6 so that the opening on the axle side of the rod 22 is sealed, and the opening on the vehicle body side of the cylinder 21 is sealed. The vehicle body side 21 is fixed to the vehicle body side blocking member 7.

  The cylinder 21 is formed by connecting an axle side cylinder 21L and a vehicle body side cylinder 21U. A rod guide 36 having a rod through hole 36h is provided at the axle side opening of the axle side cylinder 21L. A bush 37 is provided on the inner peripheral surface of the rod through hole 36h, and the outer peripheral surface RF of the rod 22 and the inner peripheral surface of the bush 37 are configured to be slidable. The vehicle body side of the rod 22 is inserted into the cylinder 21 through the rod through hole 36h.

  FIG. 3 is an enlarged cross-sectional view around the piston 23 provided on the first fork leg 11A shown in FIG. FIG. 4 is an enlarged cross-sectional view of a main part around the piston 23 shown in FIG.

  A piston 23 is provided at the end of the rod 22 inserted into the cylinder 21 on the vehicle body side. A rebound spring 40 is provided between the axle side of the piston 23 and the vehicle body side of the rod guide 36. The rebound spring 40 extends spirally along the central axis 17 outside the outer peripheral surface RF of the rod 22.

  An insertion hole 23 </ b> C for inserting the first end of the rod 22 is formed on the axle side of the piston 23. The outer peripheral surface of the portion forming the insertion hole 23C enters the spiral central hole from the opening of the spiral central hole of the rebound spring 40, and the outer peripheral surface of the portion forming the insertion hole 23C is wider than the outer peripheral surface on the vehicle body side. A spring collision surface 23D which is a suspicious surface is formed. Since the first end of the rebound spring 40 collides with the spring collision surface 23D, an extension operation beyond a certain level is prevented.

  The outer tube 15, the inner tube 16, the cylinder 21, the rod 22 and the piston 23 are provided so as to be coaxial with the central axis 17.

  On the vehicle body side of the piston 23, a sub tank connecting portion 23A is formed. The sub tank connecting portion 23 </ b> A is formed as a cylindrical portion having a smaller diameter than the diameter of the outer peripheral surface of the piston 23. The sub tank 38X is formed by a hollow rod-shaped container having a first end opening and a second end closing.

  A communication passage 23 </ b> B for communicating the gas chamber 38 </ b> U in the sub tank 38 </ b> X and the gas chamber 22 </ b> U inside the rod 22 with the balance chamber 70 is formed inside the piston 23. Thus, since the sub tank 38X communicating with the balance chamber 70 is provided, the volume of the balance chamber 70 can be expanded, and the compression ratio can be lowered even under high pressure conditions. Accordingly, the reaction force characteristic at the maximum extension is stabilized, and the steering stability can be improved.

(1-2-2 Configuration of gas chamber)
As shown in FIG. 2, the inner side of the first fork leg 11A includes an inner chamber 50 as a first air spring chamber, an outer chamber 60 as a second air spring chamber, and a third air spring chamber. A compartment is formed with the balance chamber 70. 3 and 4, lip packings 71A and 71B for maintaining the balance chamber 70 and the inner chamber 50 adjacent to each other in an airtight state, and the balance chamber 70 and the outer chamber 60 adjacent to each other are provided. Lip packings 73B and 73C for maintaining an airtight state are provided.

  The inner chamber 50 is formed by a sealed space surrounded by the vehicle body side closing member 7, the piston 23, the inner peripheral surface of the cylinder 21 between the vehicle body side closing member 7 and the piston 23, and the outer peripheral surface of the sub tank 38X. Is done.

  The outer chamber 60 includes an outer peripheral surface RF of the rod 22, an axle side fixing portion 6, inner peripheral surfaces of the inner tube 16 and the outer tube 15, a vehicle body side blocking member 7, an outer peripheral surface of the cylinder 21, and a rod guide 36. Is formed by a sealed space surrounded by the end portion on the axle side.

  The balance chamber 70 is formed by a space surrounded by the piston 23, the rod guide 36, and the inner peripheral surface of the cylinder 21 between the piston 23 and the rod guide 36.

  The gas chamber 22 </ b> U inside the rod 22 communicates with the balance chamber 70 via a communication path 23 </ b> B formed in the piston 23, and the rod 22 forms a gas chamber 22 </ b> U for adjusting the compression ratio in the balance chamber 70. Functions as a sub tank 22X.

  The sub tank 38X communicates with the balance chamber 70 via a communication path 23B formed in the piston 23, and also communicates with the gas chamber 22U of the rod 22 for adjusting the compression ratio in the balance chamber 70. A gas chamber 38U is formed.

(1-2-3. Configuration Related to Cylinder 21 and Communication Member 8)
FIG. 5 is a partial perspective view of the communication member 8 provided on the first fork leg 11A as viewed from the inside. FIG. 6 is a partial perspective view of the cylinder 21 to which the communication member 8 is attached as viewed from the inside.

  3 to 6, a cylindrical communication member 8 is provided on the outer peripheral surface of the cylinder 21 on the axle side. The inner peripheral surface of the communication member 8 slides with respect to the outer peripheral surface of the cylinder 21, and a communication passage 8 </ b> A that is a recess is formed on the inner peripheral surface of the communication member 8. Therefore, a space through which gas passes is formed between the outer peripheral surface of the cylinder 21 and the inner peripheral surface of the communication path 8A.

  A plurality of communication holes 9a to 9d are formed along the axial direction at intervals of a length L1 on the peripheral surface of the cylinder 21 where the communication path 8A of the communication member 8 is located. The length in the axial direction of the communication path 8A may be a length that allows two communication holes of the communication holes 9a to 9d to communicate with each other.

  The piston 23 has a sliding portion 23 </ b> E that abuts the inner peripheral surface of the cylinder 21 and separates the inner chamber 50 and the balance chamber 70.

  As shown in FIG. 4, the length J1 of the sliding portion 23E in the axial direction is such that two communication holes adjacent along the axial direction, for example, a communication hole 9b (first communication hole) and a communication hole 9c (second Shorter than the length L1 between the communication holes). Specifically, the length J1 of the sliding portion 23E in the axial direction is set so that the lower end of the upper communication hole 9b and the upper end of the lower communication hole 9c of the two adjacent communication holes 9b and 9c shown in FIG. It is preferable that it is shorter than the length between. However, the axial length J1 of the sliding portion 23E is the length between the upper end of the upper communication hole 9b and the lower end of the lower communication hole 9c of the two adjacent communication holes 9b and 9c. Shorter than that.

  FIG. 7 is a schematic diagram for explaining the relationship between the plurality of communication holes 9a to 9d formed in the cylinder 21 of the first fork leg 11A according to the first embodiment and the communication passage 8A formed in the communication member 8. It is.

  An example will be described in which the four communication holes 9a to 9d are arranged at intervals of the length L1 along the axial direction. As shown in FIG. 7, the communication hole 9 a (first communication hole) is formed on the most circumferential surface of the cylinder 21 on the vehicle body side. A second communication hole 9b (second communication hole) from the vehicle body side is formed on the axle side of the communication hole 9a with an interval of length L1. A third communication hole 9c (third communication hole) from the vehicle body side is formed on the axle side of the communication hole 9b with an interval of length L1. A fourth communication hole 9d from the vehicle body side is formed on the axle side of the communication hole 9c with an interval of a length L1.

  That is, on the circumferential surface of the cylinder 21, four communication holes 9a to 9d are formed along the axial direction of the cylinder 21 with an interval of a length L1 therebetween.

  The length L1 is a distance between two points indicated by the coordinate axis when the long axis of the cylinder 21 is a coordinate axis, and even if the positions of some of the communication holes 9a to 9d are displaced only in the circumferential direction. The length L1 does not change.

  As shown in FIGS. 4 and 7, when the communication member 8 is attached to the cylinder 21 so that the communication path 8A of the communication member 8 is located in a region D1 overlapping the communication holes 9a and 9b, the sliding portion of the piston 23 When 23E is located between the two communication holes 9a and 9b in the region D1, the communication between the inner chamber 50 and the balance chamber 70 is established through the two communication holes 9a and 9b and the communication passage 8A. Allowed, the internal pressure of the inner chamber 50 and the balance chamber 70 is made uniform. The two communication holes 9c and 9d located outside the region D1 are sealed by the inner peripheral surface 8B (sealing surface) of the communication member 8.

  Further, when the communication member 8 is attached to the cylinder 21 so as to be displaced in the axial direction so that the communication path 8A is located in the region D2, the sliding portion 23E of the piston 23 is connected to the two communication holes 9b and 9c in the region D2. When communicating between the inner chamber 50 and the balance chamber 70 through the communication hole 9b, the communication path 8A, and the communication hole 9c.

  Further, when the communication member 8 is attached to the cylinder 21 so as to be displaced in the axial direction so that the communication path 8A is located in the region D3, the sliding portion 23E of the piston 23 is connected to the two communication holes 9c and 9d in the region D3. When communicating between the inner chamber 50 and the balance chamber 70 through the communication hole 9c, the communication path 8A, and the communication hole 9d.

  Thus, by forming the communication holes 9 a to 9 d on the peripheral surface of the cylinder 21, the inner chamber 50 and the balance chamber 70 are allowed to communicate with each other, and the inner pressure of the inner chamber 50 and the balance chamber 70 is made uniform. Therefore, unlike the prior art, it is not necessary to form a groove on the inner peripheral surface of the cylinder in order to equalize the internal pressure. As a result, it is possible to realize an air spring structure that can equalize the internal pressure of the inner chamber 50 and the balance chamber 70 with a simple configuration.

  In addition, since the communication member 8 is configured such that two of the communication holes 9a to 9d that allow the inner chamber 50 and the balance chamber 70 to communicate with each other can be varied in the axial direction, the position of the communication member 8 in the axial direction is selected. Thereby, the air reaction force characteristic of the inner chamber 50 and the balance chamber 70 can be adjusted to a desired air reaction force characteristic.

(1-3. Operation of the first fork leg 11A)
The first fork leg 11A has a compression operation (compression side stroke) in which the inner tube 16 and the outer tube 15 approach each other as the vehicle body receives an impact, and the inner tube 16 and the outer tube 15 are connected to each other. An extension operation (extension side stroke) that moves in a direction away is performed to buffer the impact.

  In the compression side stroke, the inner chamber 50 and the outer chamber 60 are reduced in volume and the gas in the inner chamber 50 and the outer chamber 60 is compressed, so that the inner tube 16 and the outer tube 15 are separated from each other. Reaction force is generated.

  Further, in the extension side stroke, the piston 23 and the rod guide 36 move in a direction approaching each other, so that the volume of the balance chamber 70 that is a rebound air spring chamber is reduced and the gas in the balance chamber 70 is compressed. At this time, the gas sealed in the sub tank 22X by the rod 22 communicating with the balance chamber 70 and the balance chamber 70 and in the sub tank 38X in the cylinder 21 acts as an air spring, and compresses the front fork 4 in the direction. Reaction force is generated.

  When the sliding portion 23E of the piston 23 is positioned between the two communication holes facing the communication path 8A of the communication member 8 attached to the cylinder 21 in the initial stage of the compression side stroke, the two communication holes are provided. In addition, the communication between the inner chamber 50 and the balance chamber 70 is allowed through the communication passage 8A, and the internal pressure of the inner chamber 50 and the balance chamber 70 is made uniform.

  The same applies when the sliding portion 23E is located between the two communication holes facing the communication path 8A of the communication member 8 at the end of the extension side stroke.

(1-4. Air reaction force characteristics of the first fork leg 11A)
FIG. 11 is a graph showing air reaction force characteristics of a front fork according to a comparative example. The horizontal axis shows the stroke, and the vertical axis shows the reaction force by the air spring. Stroke S1 corresponds to the extended state of the front fork, and stroke S2 corresponds to the compressed state.

  In order to equalize the internal pressure in the inner chamber 50 and the balance chamber 70, a groove is formed on the inner peripheral surface of the cylinder as in the prior art, and when the enclosed pressure of the inner chamber 50 air is increased, the curve C2 indicates In addition, there is a problem that the initial load of the compression operation from the stroke S1 to the stroke S3 is increased compared to the state before the air sealing pressure is increased (curve C1).

  FIG. 8 is a graph showing the air reaction force characteristics of the first fork leg 11A according to the first embodiment. The vertical axis shows the reaction force by the air spring. Stroke S1 corresponds to the extended state of the front fork, and stroke S2 corresponds to the compressed state.

  In the first fork leg 11A according to the first embodiment in which the cylinder 21 having the communication holes 9a to 9d and the communication member 8 in which the communication path 8A is formed are provided, when the air sealing pressure of the inner chamber 50 is increased, By adjusting the position of the communication member 8, as shown by the curve C3, an increase in the initial load of the compression operation from the stroke S1 to the stroke S3 can be suppressed more than the curve C2 described above with reference to FIG. As described above, in the first fork leg 11 </ b> A, an arbitrary load characteristic can be selected by adjusting the position of the communication member 8.

(1-5. Effect of the first fork leg 11A)
The air spring structure according to the first embodiment and the second embodiment to be described later is inserted into the cylinders 21 and 21A in the axial direction from the second ends of the cylinders 21 and 21A with the first ends being closed ends. Rod 22, a piston 23 that is held by rod 22 and slides on the inner peripheral surface of cylinders 21, 21 A, and a communication member 8 provided on the outer peripheral surface of cylinders 21, 21 A is provided. Are formed in the inner chamber 50 formed as an air spring on the first end side of the piston 23, the balance chamber 70 formed as an air spring on the second end side of the piston 23, and the peripheral surfaces of the cylinders 21 and 21A. The first communication hole 9a and the second communication hole 9b formed on the peripheral surface on the second end side of the communication hole 9a. The piston 23 is in contact with the inner peripheral surface of the cylinders 21 and 21A and Room 5 And the balance portion 70 are separated by a sliding portion 23E, and the length of the sliding portion 23E in the axial direction is shorter than the length in the axial direction between the first and second communication holes 9a and 9b. Has a communication passage 8A formed to allow the inner chamber 50 and the balance chamber 70 to communicate with each other through the first and second communication holes 9a and 9b.

  Thereby, in the initial stage of the compression operation, the sliding portion 23E of the piston 23 is positioned between the first and second communication holes 9a and 9b facing the communication path 8A of the communication member 8 attached to the cylinders 21 and 21A. In this case, the communication between the inner chamber 50 and the balance chamber 70 is allowed through the first and second communication holes 9a and 9b and the communication passage 8A, and the internal pressure of the inner chamber 50 and the balance chamber 70 is made uniform. The For this reason, it is not necessary to form a passage or a groove on the inner peripheral surface of the cylinder as in the prior art, and the first and second communication holes 9a and 9b are formed on the peripheral surface of the cylinder 21 and 21A. The internal pressure in the inner chamber 50 and the balance chamber 70 defined in the cylinders 21 and 21A can be equalized by a simple configuration in which the communication member 8 is provided on the outer peripheral surface of the inner chamber 50.

  Further, by rotating the cylindrical communication member 8 around its axis, the phases of the first and second communication holes 9a and 9b and the communication passage 8A can be shifted, and the inner chamber 50, the balance chamber 70, The communication between the inner chamber 50 and the balance chamber 70 can be easily switched.

  The communication member 8 may be formed in a tubular shape instead of a cylindrical shape, and both ends thereof may be connected to the first and second communication holes 9a and 9b, respectively.

  Further, in the air spring structure, the cylinders 21 and 21A further include a third communication hole 9c formed in the peripheral surface on the second end side of the second communication hole 9b, and the axial length of the sliding portion 23E is provided. Is shorter than the axial length between the second communication hole 9b and the third communication hole 9c, and the communication path 8A allows two of the first communication hole 9a to the third communication hole 9c to communicate with each other. .

  Accordingly, the axial position of the communication member 8 is selected so that the communication passage 8A communicates the inner chamber 50 and the balance chamber 70 through two of the first communication hole 9a to the third communication hole 9c. can do. For this reason, the air reaction force characteristic of the inner chamber 50 and the balance chamber 70 can be adjusted to a desired air reaction force characteristic.

  The communication member 8 having an air spring structure seals the third communication hole 9c when the communication path 8A connects the inner chamber 50 and the balance chamber 70 through the first communication hole 9a and the second communication hole 9b. It has an inner peripheral surface 8B.

  Thereby, it is possible to prevent air leakage from the third communication hole 9c other than the first communication hole 9a and the second communication hole 9b that allow the inner chamber 50 and the balance chamber 70 to communicate with each other through the communication path 8A.

  In the air spring structure, a gas chamber 22 </ b> U communicating with the balance chamber 70 is further formed inside the rod 22.

  Thereby, the balance chamber 70 is expanded, and a desired air reaction force characteristic in a direction in which the front fork 4 is compressed in the extending operation can be realized.

(Embodiment 2)
(2-1. Configuration related to cylinder 21A)
FIG. 9 is a partial perspective view of the cylinder 21A to which the communication member 8 of the first fork leg 11A according to the second embodiment is attached as viewed from the inside. FIG. 10 is a schematic diagram for explaining the relationship between the communication holes 9a to 9g formed in the cylinder 21A of the first fork leg 11A according to the second embodiment and the communication passage 8A formed in the communication member 8. . The same components as those described above with reference to FIG. 6 are denoted by the same reference numerals. Detailed description of these components will not be repeated.

  Four communication holes 9a to 9d are formed in the circumferential surface of the cylinder 21A along the axial direction with an interval of a length L1. Further, on the circumferential surface of the cylinder 21A, three communication holes 9e to 9g are formed along the axial direction at intervals of a length L1 at positions spaced from the communication holes 9a to 9d in the circumferential direction. The communication hole 9e is disposed between the communication hole 9a and the communication hole 9b in the axial direction. More precisely, the coordinate of the communication hole 9e indicated by the coordinate axis along the axial direction is located between the coordinate of the communication hole 9a indicated by the coordinate axis and the coordinate of the communication hole 9b. Similarly, the communication hole 9f is disposed between the communication hole 9b and the communication hole 9c in the axial direction. The communication hole 9g is disposed between the communication hole 9c and the communication hole 9d in the axial direction.

  When the communication member 8 is attached to the cylinder 21A so that the communication path 8A is positioned in the region D1 shown in FIG. 10, the sliding portion 23E of the piston 23 is positioned between the two communication holes 9a and 9b in the region D1. When this is done, the communication between the inner chamber 50 and the balance chamber 70 is allowed through the two communication holes 9a and 9b and the communication passage 8A, and the internal pressure between the inner chamber 50 and the balance chamber 70 is made uniform. . The five communication holes 9c to 9g located outside the range of the region D1 are sealed by the inner peripheral surface 8B (sealing surface) of the communication member 8.

  The communication member 8 according to the second embodiment is configured to be shifted with respect to the cylinder 21 in the axial direction and attached in the circumferential direction.

  When the communication member 8 is attached to the cylinder 21A so as to be displaced in the circumferential direction and the axial direction so that the communication path 8A is located in the region D4, the sliding portion 23E of the piston 23 is connected to the two communication holes in the region D4. When positioned between 9e and 9f, communication between the inner chamber 50 and the balance chamber 70 is allowed through the two communication holes 9e and 9f and the communication passage 8A. The five communication holes 9a to 9d and the communication hole 9g located outside the region D4 are sealed by the inner peripheral surface 8B (sealing surface) of the communication member 8.

  The length L2 along the axial direction between the communication hole 9a on the vehicle body side in the region D1 and the communication hole 9e on the vehicle body side in the region D4 is the length between the two communication holes 9a and 9b in the region D1. Shorter than L1. For this reason, for example, adjusting the air reaction force characteristic between the region D1 and the region D4 can adjust the air reaction force property more finely than adjusting between the region D1 and the region D2.

(2-2. Effects related to the cylinder 21A)
Cylinder 21A having an air spring structure is provided at third communication holes 9c and 9d formed on the peripheral surface on the second end side of second communication hole 9b, and at a position away from third communication holes 9c and 9d in the circumferential direction. The fourth communication hole 9e formed and the fifth communication holes 9f and 9g formed on the peripheral surface on the second end side of the fourth communication hole 9e are further provided, and the cylinder 21A includes the communication holes 9a and 9b. A set of communication holes 9b and 9c, a set of communication holes 9c and 9d, a set of communication holes 9e and 9f, a set of communication holes 9f and 9g, and the set of the plurality of communication holes is an axis of the cylinder 21A. They are formed at different positions in the direction and the circumferential direction.

  Thereby, the air reaction force characteristic can be adjusted more finely.

  In the communication member 8 having the air spring structure, the communication path 8A includes a set of communication holes 9a and 9b, a set of communication holes 9b and 9c, a set of communication holes 9c and 9d, a set of communication holes 9e and 9f, a communication hole 9f and An inner peripheral surface 8B that seals each of the communication holes included in the other one of the plurality of sets of communication holes when the plurality of communication holes included in one of the groups of 9g communicate with each other. Have

  Thereby, it is possible to prevent air leakage from communication holes other than the communication hole 9a and the communication hole 9b that allow the inner chamber 50 and the balance chamber 70 to communicate with each other through the communication path 8A.

(Embodiment 3)
(Example of changing the arrangement of communication holes)
As shown in FIG. 7, the four communication holes 9 a to 9 d do not necessarily have to be aligned in a single line along the long axis of the cylinder 21. Even if some positions of the communication holes 9a to 9d are slightly shifted in the circumferential direction, there is no problem as long as two of the communication holes 9a to 9d are communicated by the communication path 8A of the communication member 8.

  Further, regarding the arrangement of the seven communication holes 9a to 9g shown in FIG. 11, it is not always necessary that the communication holes 9a to 9d and the communication holes 9e to 9g are completely aligned along the long axis of the cylinder 21A. Absent.

  Further, the long axis of the communication path 8A of the communication member 8 need not be formed so as to be parallel to the long axes of the cylinders 21 and 21A. The communication path 8A includes two of the plurality of communication holes. What is necessary is just to be formed so that it may mutually communicate.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

3 Rear suspension 4 Front fork 8 Communication member 8A Communication path 8B Inner peripheral surface (sealed surface)
9a-9g Communication hole (1st communication hole, 2nd communication hole, 3rd communication hole, 4th communication hole, 5th communication hole)
11A First fork leg 11B Second fork leg 12A First bracket 12B Second bracket 13 Steering shaft 15 Outer tube 16 Inner tube 21 Cylinder 22 Rod 22U Gas chamber (second end chamber)
23 Piston 23E Sliding part 50 Inner chamber (first end chamber)
60 Outer chamber 70 Balance chamber (second end chamber)

Claims (6)

A cylinder whose first end is a closed end;
A rod inserted axially into the cylinder from a second end of the cylinder;
A piston that is held by the rod and slides on the inner peripheral surface of the cylinder;
A communication member provided on the outer peripheral surface of the cylinder,
The cylinder is
A first end chamber formed as an air spring on the first end side of the piston;
At least a part of a second end chamber formed as an air spring on the second end side of the piston;
A first communication hole formed in the peripheral surface of the cylinder;
A second communication hole formed in the peripheral surface on the second end side of the first communication hole;
The piston has a sliding portion that abuts on an inner peripheral surface of the cylinder and separates the first end chamber and the second end chamber,
The axial length of the sliding portion is shorter than the axial length between the first communication hole and the second communication hole,
The communication member includes an air spring formed to communicate the first end chamber and the second end chamber through the first communication hole and the second communication hole. Construction. The cylinder further includes a third communication hole formed in the peripheral surface on the second end side of the second communication hole;
The axial length of the sliding portion is shorter than the axial length between the second communication hole and the third communication hole,
2. The air spring structure according to claim 1, wherein the communication passage allows two of the first communication hole to the third communication hole to communicate with each other.   The communication member seals the third communication hole when the communication path connects the first end chamber and the second end chamber through the first communication hole and the second communication hole. The air spring structure according to claim 2, which has a sealing surface. The cylinder includes a third communication hole formed in the peripheral surface on the second end side of the second communication hole, and a fourth communication hole formed at a position away from the third communication hole in the circumferential direction. And a fifth communication hole formed in the peripheral surface on the second end side of the fourth communication hole,
A plurality of sets of communication holes including two of the first communication hole to the fifth communication hole;
2. The air spring structure according to claim 1, wherein the plurality of sets of communication holes are formed at positions different from each other in an axial direction and a circumferential direction of the cylinder.   In the communication member, when the communication path allows a plurality of communication holes included in one of the plurality of communication hole sets to communicate with each other, the other one of the plurality of communication hole sets is provided. The air spring structure according to claim 4, further comprising a sealing surface that seals each of the communication holes included in the air spring.   The air spring structure according to any one of claims 1 to 5, wherein a part of the second end chamber is further formed inside the rod.

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